Harnessing ocean power to provide heat and air conditioning

Tuesday, 01 December 2015 07:12

The AquaEdge 23XRV chiller. (Image source: Evergreen)The Cape Town V&A Waterfront’s Silo District is recognised as one of the most advanced and environmentally-friendly developments, not just in South Africa but throughout the continent

The Silo District project is due for completion in 2017, once an additional four silo developments are fully-operational.

A division of United Technologies Corp, heating and air-conditioning solutions provider Carrier is playing a central role in the final stage of the Silo District project at the V&A Waterfront in Cape Town, South Africa, with the installation of a 6MW cooling plant on the last four of six silos.

The AquaEdge 23XRV variable speed screw chiller is a highly-efficient cooling solution that achieves a coefficient of performance (COP) between 10.37 and 16.04 under various conditions. COP is a measurement of efficiency obtained by dividing the power output by the power input. The higher the number, the more efficient the system.

Carrier business development manager Jaco Smal described the project recently, saying, “By circulating seawater through heat exchangers, the system does not require cooling towers to reject heat into the atmosphere, rather, it rejects unwanted heat into the ocean. As a result, the system gains from the efficiencies associated with water cooling, and avoids the pitfall of water usage through evaporation in cooling towers.”

Robust, efficient technologyThe Carrier AquaEdge 23XRV chiller also makes use of non-ozone-depleting HFC-134a refrigerant and next-generation, patented screw compressor technology that features a tri-rotor. Smal explained, “This unique chiller is able to use the variable frequency drive (VFD) to reduce speed and optimise operation, independent of ambient conditions. As a result, it is able to precisely match building load and conserve energy, making it the world’s most efficient chiller in these conditions.”

In addition to breaking this efficiency barrier, the AquaEdge 23XRV features robust and flexible operation with a wide operating envelope and surge-free compression. The innovative design and high-quality construction makes the AquaEdge 23XRV chiller the most modern and efficient choice in water-cooled plants. It is available is sizes from 250 tonnes to 550 tonnes (879kW to 1,934kW) Nominal.

The Carrier cooling plant will provide cooling and heating solutions for four new developments in the V&A Waterfront’s Silo District. The Silo District will introduce over 35,000m2 of mixed use, sustainable developments including new corporate offices, a residential development, a health club, an internationally-branded hotel, plus over 1,050 additional parking bays.

Silos 1 and 2 developments were completed in mid-2014, and use the waters of the Atlantic Ocean in the surrounding harbour to provide cooling and heating. Silo 1 ranks as the only South African building to receive a six-Star ‘As Built’ GBCSA rating, which signifies world-leadership in sustainable development. Carrier is workng to provide the same cooling and heating solutions to Silos 3 to 6.

When completed, the Silo District will sit on top of a 2,750 parking bay super basement. Approximately 2,500 people will work in the district daily. The district is also home to the Zeitz Museum of Contemporary Art Africa (Zeitz MOCAA), currently under development. In total, the project is expected to cost R2.5bn (US$177.6mn). In a 2014 independent economic impact study commissioned by the V&A Waterfront, the expected nominal contribution to GDP from future developments is R29.9bn by 2027.